Grinding-machine.



G. BLECHER.

GRINDING MACHINE.

APPLICATION FILED AUG. 2a, 1913.

Patented Sept. 1, 1914,

2 SHEETS-SHEET 1 C. BLECHER.

' GRINDING MACHINE.

APPLICATION FILED we. 2a, 1913.

1,109,277. V Patented Sept. 1, 1914.

, 2 SHEBTS8HEET 2.

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CARL BLECHER, OF BERLIN, GERMANY.

GRINDING-MACHINE.

To all whom it may concern Be it known that I, CARL BLECHER, citizen ofthe free town of Hamburg, residing at 110 Alexandrinenstrasse, Berlin,in the German Empire, have invented certain new and useful Improvementsin Grinding- Machines, of which the following is a specifieation;

This invention relates to a machine for grinding cylindrical bodies bymeans of a flat grinding element and is particularly adapted forgrinding copper printing cylinders. Hitherto in grinding machines ofthis type it has been proposed to allow the fiat grinding element torotate while moving it longitudinally over the work. In order toobviate-scratches such as may be caused by particles becoming loosenedat the center of the grinding element. the latter has also been movedtransversely over the work; Unless the grinding element is movedtransversely over the Work, there is also the danger of a projection orboss forming at the center-of the grinding elementif its pivotal axisdoes not always intersect the axis of the work.

According to the present invention, the grinding action'is attained byimparting-a circular motion to the grinding element about an eccentricaxis while to obviate scratches and obtain uniform wear, the grindingelement is slowly rotated about its geometric axis, this rotation beinghowever immaterial to the grinding operation. The rotation of thegrinding element about its geometric axi's may be very small and takesplac only to such an extent that all the points on the face of thegrinding element are brought as far as possible uniformly into action onthe line of contact with the work, in order to prevent irregular wear orthe formation of grooves in the face of the grinding element. In thismanner, a uniform grinding action is obtained, and since all the pointson the face of the grinding element, come equally into action, incontradistinction to a grinding element rotated for grinding purnoses ata high speed solely about its geometric axis, the danger of particlesbreaking off in the center of the grinding element is obviated. Thegrinding element can be comparatively easily mounted and driven and maybe supported on a shaft carried in fixed bearings so that itmay bepressed a ainst the work on axially moving the'shaft.

Specification of Letters Patent.

Application filed August 28, 1913.

Serial No. 787,121.

In order that the invention may be more,

Patented Sept. 1, 1914.

clearly understood, reference is made to the accompanying drawings,illustrating two embodiments of the invention by way of example.

Figure 1 is a side view, partly in s ti of such parts of the machine asare'necessary for the invention to be understood. Fig. 2 is a plan viewof Fig. 1 and Fig. 3 a side view, partly in section, on the line m-x ofFig. 2. Figs. 4 and 5 are side and lan views respectively of a slightlymodified form of Fig. 1. Referring to Figs. 1, 2 and 3 of the drawingszThe flat grinding element a, which rests upon the work to to be ground,is supported in a tool holder 7) which carries a disk-shaped head plateI) having a circular recess 111 which is rotatably fitted an eccentric 0mounted on a rotatable driving shaft (1 carried in fixed bearings. On acollar b fixed on the tool holder 6 is secured a spur wheel 6 meshingwith a toothed rack having an eye at its end f through which is fitted avertical rod g so that the rod f may move up and down at its end f overthe rod 9. A weight g secured to one end of a cord 2', which passes overa pulley n on the rod 9 and is secured at its other end to a hook Z onthe end of the rack f, balances the weight of the rack f at this end.The toothed rack f passes through a guide shoe 72 which is loosely androtatably mounted on the collar 6 of the tool holder (2. This permits ofa relative movement between the rack f and holder 6 thus insuring theengagement of the teeth between the spur wheel 6 and rack If the drivingshaft (Z is carried in fixed bearings as hereinbefore described, thework 111 must be slowly rotated and moved axially to and fro in orderthat the whole of its cylindrical surface may in succession be subjectedto the grinding element a. If, for this purpose, the work is mounted ona slide similar to a lathe carriage, the vertical rod g must be securedto the same slide. The rod 9 will then slowly move the rack f to and frothrough the shoe h during the axial feed of the work and thus impart acorresponding slow to and fro rotary motion to the spur wheel 6 andgrinding element a about their common axis, this rotary motion beingpreferably about 180 or slightly more for each to and fro movement ofthe work w. By mounting the shaft d in a similar manner to the drivingshafts of milling machines or the like, the grinding element a can bepressed down upon the work w with the necessary pressure by the downwardmovement of the shaft (1. Apart from the rotation of the spur Wheel 6 inone direction about its center during the feed of the work in onedirection, the spur wheel e rolls to and fro on the rack f owing to thethrow imparted by the eccentric to the spur wheel e in the direction ofthe axis of the work. Thus, during the feed of the work in onedirection, the grinding element a during its circular motion about theaxis of the shaft d, and in addition to its slow rotation in onedirection about its center, due to the slow sliding movement of the rackf, also makes a rocking movement about its center, this rocking movementbeing alternately added to and subtracted from its slow rotation. Thisadditional rocking motion of the grinding element about its center is,however, so slow that it is of no importance to the grinding action.

In the modification illustrated in Figs. 4 and 5, a spur wheel is isemployed instead of the toothed rack f of Figs. 1 to 3. The spur wheelis is mounted on a rod m having a slotted guide m embracing the verticalrod 9 which in this case may be fixed. In order to rotate the spur wheelat a slow speed, the latter is driven by means of a flexible shaft 0from any suitable source of power. In the case, when this eccentric c isrotated by the shaft d, the spur wheel e rolls on the spur wheel is,during its circular motion about the axis of the shaft d, in a similarmanner to the rolling of the spur wheel e on the rack f in Fig. 1, andis also rocked to and fro about its center, this rocking motion beingalternately added to and subtracted from the slow rotation imparted bythe spur wheel k. Thus in this case the compound rotary motion of thegrinding element (1, obtained by the rack f in Figs. 1 to 3, is alsoobtained during the circular grinding motion about the shaft d.

Assuming now that the spur wheels e and I: in Figs. 4 and 5 are removed,and that the grinding element a does not rest on the work 10; then itwill be clear that the grinding element a will describe a circularmovement about the shaft d together with the cocentric 0 without itspivot pin m rotating in the hollow bearing 6 of the rod 111.. It wouldthus act as if its pivot pin m were in one piece with the bearing 6 Assoon as the grinding element a bears on the work, however, the friction,during the grinding operation, arrests the grinding element a and pin mand tends to set the grinding element a into an irregular rotary motionand 'to rotate the pin m in the bearing b the speed of the rotationbeing greatest in the two positions of the circular motion of thegrinding element where the frictional forces on the grinding element acton one side of its center, that is, in the extreme positions laterallyof the axis of the work. In the other extreme positions, where thegrinding element lies symmetrically over the axis of the work, thisrotar motion will be practically nothing, since the frictional forces onboth sides of the center of'the grinding element act in oppositedirections, thus equalizing each other. The direction of the rotation ofthe grinding element about its center will be the same as the circularmotion owing to the frictional moments. In order that the extent of thisirregular rotation about the center of the grinding element, due to thefrictional turning moments and which does not permit of the desiredrelative movement between the grinding element and the work essential togrindin may not be too great, so that the aforesaid relative movementwill take place, means are provided for retarding this irregular mo-,tion, this means, as shown in Fig. 4 comprising a pinching screw macting on the pivot pin m By correspondingly tightening the screw m, therotation of the pin m and grinding element a relatively to the rotationof the eccentric 0 can thus be so regulated that it is limited withoutbeing entirely prevented, thus insuring uniform wear of the face of thegrinding element. In this manner, a slight rotation of the grindingelement and variation in its position can be attained without the use ofspecial mechanism such as the rack f or spur wheel is. The compoundrotary motion may, however, be imparted to the grinding element in anyother suitable manner.

I claim 1. In a machine for grinding cylindrical bodies, a fiat grindingelement, means for imparting a circular motion thereto about an axiseccentric to said element, means for imparting a slow rotary motion tosaid element about its geometric axis, and means for imparting anoscillatory motion to said element about its geometric axis, saidoscillatory motion being alternately added to and subtracted from saidrotary motion.

2. In a machine for grinding cylindrical bodies movable to and froaxially, a flat grinding element, means for imparting a circular motionto said element about a fixed axis eccentric thereto, and means forimparting a small reciprocatory angular motion to said element about itsgeometric axis during the axial movement of the work, the change periodof the angular motion corresponding to the change period of the to andfro movement of the work.

3. In a machine for grinding cylindricalbodies, a stationary rotaryshaft, an eccentric thereon, a flat grinding element driven by saideccentric, means for simultaneously imparting a slow rotary motion tosaid element about its geometric axis, and means for simultaneouslyimparting an oscillatory motion to said element about its geometricaxis.

4. In a machinefor grinding cylindrical bodies, a stationary rotaryshaft, a flat grinding element rotatable about its geometric axis, aneccentric on said shaft imparting a circular motion to said elementabout said shaft, a gear wheel rotatable with said element, a memberwith which said gear wheel makes rolling engagement and means forimparting a slow movement to said member for transmitting a slow rotarymotion to said wheel andelement.

5.'In a machine for grinding cylindrical bodies movable to and froaxially, a sta tionary rotary shaft, a flat grinding element rotatableabout its geometric axis, an eccentric on said shaft imparting acircular motion to said element about said shaft, a gear wheel rotatablewith said element, and a movable transmission member engaging with saidgear wheel for'imparting a slow rotary motion to said wheel and element.

(3. In a machine for grinding cylindrical bodies, movable to and froaxially, a. stationary rotary shaft, an eccentric rotatable therewith, aflat grinding element, rotatable on said eccentric, a rotarytransmission member rotatable With said element and a transmissionmember making rolling engagement with said rotary member.

7. In a machine for grinding cylindrical bodies, a stationary rotaryshaft, an eccentric disk rotatable therewith, a flat grinding element, aholder for said element having a circular recess in which said disk isrotatably fitted, a gear wheel rotatable with said element, a memberwith which said wheel i makes rolling engagement and means for impartinga slow movement to said member for transmitting a slow rotary motion tosaid wheel and element.

8, In a machine for grinding cylindrical bodies, a stationary rotaryshaft, a flat grinding element rotatable about its geometric axis, aneccentric on said shaft imparting a circular motion to-saidelement aboutsaid shaft, a gear Wheel rotatable with said element, a slowly rotatedgear wheel meshing with the aforesaid gear wheel, and means for enablingsaid second-mentioned gear wheel to move in circular motion with saidelement.

9. In a machine for grinding cylindrical bodies, a stationary rotaryshaft, an eccentric thereon, a strap surrounding said eccentric, ahollow bearing carried by said strap, a flat grinding element, a pivotpin on said element fitting in said bearing, and a pinching screw pasingthrough said bearing and engaging said pin for retarding the rotation ofsaid element about its geometric axis.

In testimony whereof I have afiixed my signature in presence of twowitnesses.

CARL BLE CHER.

Witnesses:

VVOLDEMAR HAUr'r, HAn'rwrc P. NEUBANCE.

